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authorCedric Le Goater <clg@fr.ibm.com>2006-10-02 02:19:00 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-02 07:57:25 -0700
commit9ec52099e4b8678a60e9f93e41ad87885d64f3e6 (patch)
treea68fe051b39f8f8e8be469cbd3c2f653b9b71a9d /kernel
parent1a657f78dcc8ea7c53eaa1f2a45ea2315738c15f (diff)
[PATCH] replace cad_pid by a struct pid
There are a few places in the kernel where the init task is signaled. The ctrl+alt+del sequence is one them. It kills a task, usually init, using a cached pid (cad_pid). This patch replaces the pid_t by a struct pid to avoid pid wrap around problem. The struct pid is initialized at boot time in init() and can be modified through systctl with /proc/sys/kernel/cad_pid [ I haven't found any distro using it ? ] It also introduces a small helper routine kill_cad_pid() which is used where it seemed ok to use cad_pid instead of pid 1. [akpm@osdl.org: cleanups, build fix] Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sys.c6
-rw-r--r--kernel/sysctl.c30
2 files changed, 30 insertions, 6 deletions
diff --git a/kernel/sys.c b/kernel/sys.c
index 3a4776e8f16..2314867ae34 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -92,7 +92,8 @@ EXPORT_SYMBOL(fs_overflowgid);
*/
int C_A_D = 1;
-int cad_pid = 1;
+struct pid *cad_pid;
+EXPORT_SYMBOL(cad_pid);
/*
* Notifier list for kernel code which wants to be called
@@ -773,10 +774,9 @@ void ctrl_alt_del(void)
if (C_A_D)
schedule_work(&cad_work);
else
- kill_proc(cad_pid, SIGINT, 1);
+ kill_cad_pid(SIGINT, 1);
}
-
/*
* Unprivileged users may change the real gid to the effective gid
* or vice versa. (BSD-style)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index a79ccf9d113..8020fb273c4 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -68,7 +68,6 @@ extern int sysrq_enabled;
extern int core_uses_pid;
extern int suid_dumpable;
extern char core_pattern[];
-extern int cad_pid;
extern int pid_max;
extern int min_free_kbytes;
extern int printk_ratelimit_jiffies;
@@ -137,6 +136,9 @@ static int parse_table(int __user *, int, void __user *, size_t __user *,
static int proc_do_uts_string(ctl_table *table, int write, struct file *filp,
void __user *buffer, size_t *lenp, loff_t *ppos);
+static int proc_do_cad_pid(ctl_table *table, int write, struct file *filp,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
+
static ctl_table root_table[];
static struct ctl_table_header root_table_header =
{ root_table, LIST_HEAD_INIT(root_table_header.ctl_entry) };
@@ -543,10 +545,10 @@ static ctl_table kern_table[] = {
{
.ctl_name = KERN_CADPID,
.procname = "cad_pid",
- .data = &cad_pid,
+ .data = NULL,
.maxlen = sizeof (int),
.mode = 0600,
- .proc_handler = &proc_dointvec,
+ .proc_handler = &proc_do_cad_pid,
},
{
.ctl_name = KERN_MAX_THREADS,
@@ -2427,6 +2429,28 @@ proc_minmax:
}
#endif
+static int proc_do_cad_pid(ctl_table *table, int write, struct file *filp,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct pid *new_pid;
+ pid_t tmp;
+ int r;
+
+ tmp = pid_nr(cad_pid);
+
+ r = __do_proc_dointvec(&tmp, table, write, filp, buffer,
+ lenp, ppos, NULL, NULL);
+ if (r || !write)
+ return r;
+
+ new_pid = find_get_pid(tmp);
+ if (!new_pid)
+ return -ESRCH;
+
+ put_pid(xchg(&cad_pid, new_pid));
+ return 0;
+}
+
#else /* CONFIG_PROC_FS */
int proc_dostring(ctl_table *table, int write, struct file *filp,